/**
 * TrackChangesPreviewController — F7 vscode layer (spec §6.2/§6.4). Owns one
 * sealed webview panel per markdown document, beside the source editor. On open /
 * debounced edit / F6 baseline-epoch change it reads the baseline (from the
 * reused DiffViewController) + the live buffer, runs the pure render engine, and
 * posts the HTML. Pure read-only: never mutates the document, sidecar, or
 * baseline (INV-20). The webview is sealed: local assets only, strict CSP,
 * per-load nonce, no network (INV-21).
 */
import * as path from "node:path";
import { randomBytes } from "node:crypto";
import * as vscode from "vscode";
import type { DiffViewController } from "./diffViewController";
import type { AttributionController } from "./attributionController";
import type { ProposalController } from "./proposalController";
import { renderReview, renderPlain, diffBlocks, landedTextOf, type BlockOp } from "./trackChangesModel";
import { isAuthorable } from "./workspacePath";
import type { EditFlow, EditTarget } from "./editFlow";

const VIEW_TYPE = "cowriting.trackChangesPreview";
const DEBOUNCE_MS = 150;

/**
 * Inbound webview→host messages (intent only — the sealed webview never mutates,
 * INV-21/35). F10 carried the annotations toggle + ✓/✗ proposal decisions; F11
 * adds the toolbar intents (pin baseline / ask Claude).
 */
type ToolbarMsg =
  | { type: "setMode"; mode: "on" | "off" }
  | { type: "accept"; proposalId: string }
  | { type: "reject"; proposalId: string }
  | { type: "pinBaseline" }
  | { type: "askClaude"; scope: "document" }
  | { type: "askClaude"; scope: "selection"; start: number; end: number }
  | { type: "acceptAll" }
  | { type: "rejectAll" };

export class TrackChangesPreviewController implements vscode.Disposable {
  private readonly disposables: vscode.Disposable[] = [];
  private readonly panels = new Map<string, vscode.WebviewPanel>();
  private readonly lastModel = new Map<string, BlockOp[]>();
  private readonly debounces = new Map<string, NodeJS.Timeout>();
  /** F10: per-panel annotations mode — on (default) shows review marks, off is clean. */
  private readonly mode = new Map<string, "on" | "off">();
  /** F10 (PUC-6): off-panel indicator of pending proposals on the active doc. */
  private readonly statusItem = vscode.window.createStatusBarItem(vscode.StatusBarAlignment.Right, 88);

  constructor(
    private readonly diffView: DiffViewController,
    private readonly extensionUri: vscode.Uri,
    private readonly attribution: AttributionController,
    private readonly proposals: ProposalController,
    private readonly editFlow: EditFlow,
  ) {
    this.disposables.push(
      // F11 (SLICE-5): the editor/title gateway passes the tab's resource Uri;
      // the palette / keybinding pass nothing → fall back to the active editor.
      // #41: the explorer/tab right-click also passes the clicked Uri, which may
      // not be an open document yet — open it so we preview the clicked file, not
      // whatever happens to be the active editor.
      vscode.commands.registerCommand("cowriting.showTrackChangesPreview", async (uri?: vscode.Uri) => {
        if (uri) {
          const open = vscode.workspace.textDocuments.find((d) => d.uri.toString() === uri.toString());
          this.show(open ?? (await vscode.workspace.openTextDocument(uri)));
          return;
        }
        this.show(vscode.window.activeTextEditor?.document);
      }),
      vscode.workspace.onDidChangeTextDocument((e) => this.onEdit(e.document)),
      this.diffView.onDidChangeBaseline(({ uri }) => this.refreshByUri(uri)),
      this.proposals.onDidChangeProposals(({ uri }) => {
        this.refreshByUri(uri);
        this.updateStatus(uri);
      }),
      this.statusItem,
    );
    this.statusItem.command = "cowriting.showTrackChangesPreview";
  }

  private isMarkdown(document: vscode.TextDocument): boolean {
    return document.languageId === "markdown";
  }

  /** Open or reveal the preview for a markdown document (PUC-1). */
  show(document: vscode.TextDocument | undefined): void {
    if (!document || !this.isMarkdown(document)) {
      void vscode.window.showWarningMessage(
        "Cowriting: open a Markdown document to use the track-changes preview (F6 covers other files).",
      );
      return;
    }
    const key = document.uri.toString();
    const existing = this.panels.get(key);
    if (existing) {
      existing.reveal(vscode.ViewColumn.Beside);
      this.refresh(document);
      return;
    }
    const name = path.basename(document.uri.path) || "untitled";
    const panel = vscode.window.createWebviewPanel(
      VIEW_TYPE,
      `Review: ${name}`,
      { viewColumn: vscode.ViewColumn.Beside, preserveFocus: true },
      {
        enableScripts: true,
        retainContextWhenHidden: false,
        localResourceRoots: [vscode.Uri.joinPath(this.extensionUri, "out", "media")],
      },
    );
    panel.webview.html = this.shellHtml(panel.webview);
    panel.onDidDispose(
      () => {
        this.panels.delete(key);
        this.lastModel.delete(key);
        this.mode.delete(key);
        // A panel is gone: re-show the off-panel indicator if proposals remain.
        this.updateStatus(key);
      },
      null,
      this.disposables,
    );
    // F10/F11: the webview posts the annotations toggle, ✓/✗ proposal decisions,
    // and (F11) the toolbar intents (pin baseline / ask Claude) back to the host.
    panel.webview.onDidReceiveMessage(
      (m: ToolbarMsg) => this.handleWebviewMessage(document, m),
      null,
      this.disposables,
    );
    this.panels.set(key, panel);
    // A panel is now open for this doc — the off-panel indicator is redundant.
    this.hideStatus();
    this.refresh(document);
  }

  /**
   * Route an inbound webview intent through the existing seams (INV-35): the
   * annotations toggle + ✓/✗ proposal decisions (F10) and the toolbar gestures
   * (F11). Pin targets the PREVIEWED document (`DiffViewController.pin`), not the
   * active editor — the preview knows its bound doc (§6.7).
   */
  private handleWebviewMessage(document: vscode.TextDocument, m: ToolbarMsg): void {
    const key = document.uri.toString();
    if (m?.type === "setMode" && (m.mode === "on" || m.mode === "off")) {
      this.mode.set(key, m.mode);
      this.refresh(document);
    } else if (m?.type === "accept" && m.proposalId) {
      void this.proposals
        .acceptById(this.proposals.keyFor(document), m.proposalId)
        .then(() => this.refresh(document));
    } else if (m?.type === "reject" && m.proposalId) {
      void this.proposals.rejectByIdInPlace(this.proposals.keyFor(document), m.proposalId).then(() => this.refresh(document));
    } else if (m?.type === "pinBaseline") {
      // F6 baseline store re-render arrives via the onDidChangeBaseline subscription.
      this.diffView.pin(document);
    } else if (m?.type === "askClaude") {
      const target: EditTarget =
        m.scope === "selection" ? { kind: "range", start: m.start, end: m.end } : { kind: "document" };
      void this.editFlow.askClaude(document, target);
    } else if (m?.type === "acceptAll") {
      // #46 (INV-42): batch-accept every pending proposal on this doc, then report.
      void this.acceptAll(document);
    } else if (m?.type === "rejectAll") {
      void this.rejectAll(document);
    }
  }

  /**
   * #46 (INV-42): apply every pending proposal on the document through the F4
   * accept seam (orphan-skip) and report the applied-vs-skipped tally. No
   * confirmation dialog — VS Code undo restores (parity with single accept).
   * Public so the `cowriting.acceptAllProposals` command can reach it for the
   * active doc (not only the webview button).
   */
  async acceptAll(document: vscode.TextDocument): Promise<void> {
    const { applied, skipped } = await this.proposals.acceptAllProposals(document);
    this.refresh(document);
    if (applied === 0 && skipped === 0) return;
    const skipNote = skipped > 0 ? `, ${skipped} skipped (target text changed — undo or reject)` : "";
    void vscode.window.showInformationMessage(
      `Cowriting: accepted ${applied} proposal${applied === 1 ? "" : "s"}${skipNote}.`,
    );
  }

  /** #64 (INV-53): revert every pending proposal on the document; report the count. */
  async rejectAll(document: vscode.TextDocument): Promise<void> {
    const { reverted } = await this.proposals.rejectAll(document);
    this.refresh(document);
    if (reverted > 0) {
      void vscode.window.showInformationMessage(
        `Cowriting: rejected ${reverted} proposal${reverted === 1 ? "" : "s"}.`,
      );
    }
  }

  private onEdit(document: vscode.TextDocument): void {
    const key = document.uri.toString();
    if (!this.panels.has(key)) return;
    const pending = this.debounces.get(key);
    if (pending) clearTimeout(pending);
    this.debounces.set(
      key,
      setTimeout(() => {
        this.debounces.delete(key);
        this.refresh(document);
      }, DEBOUNCE_MS),
    );
  }

  private refreshByUri(uri: string): void {
    const doc = vscode.workspace.textDocuments.find((d) => d.uri.toString() === uri);
    if (doc) this.refresh(doc);
  }

  /** Recompute the model + post HTML to the panel for its current mode (no-op if no panel). */
  refresh(document: vscode.TextDocument): void {
    const key = document.uri.toString();
    const panel = this.panels.get(key);
    if (!panel) return;
    const mode = this.mode.get(key) ?? "on";
    const current = document.getText();
    const baseline = this.diffView.getBaseline(key);
    const baselineText = baseline?.text ?? current; // no baseline → no change-marks
    const ops = diffBlocks(baselineText, current);
    this.lastModel.set(key, ops);
    // F11 (PUC-1/7): edit controls are inert on a non-authorable doc (reading stays allowed).
    const authorable = isAuthorable(document.uri.scheme);
    if (mode === "off") {
      void panel.webview.postMessage({ type: "render", mode, html: renderPlain(current), authorable });
      return;
    }
    const spans = this.attribution.spansFor(document);
    const proposals = this.proposals.listProposals(document);
    // F12/#64 (INV-50): count added/removed against the LANDED text (current minus
    // pending proposals), matching the body — a pending change shows once, as a
    // proposal, and is not also tallied as a landed add/remove.
    const landedOps = diffBlocks(baselineText, landedTextOf(current, proposals));
    const summary = {
      added: landedOps.filter((o) => o.kind === "added").length,
      removed: landedOps.filter((o) => o.kind === "removed").length,
      proposals: proposals.length,
    };
    void panel.webview.postMessage({
      type: "render",
      mode,
      html: renderReview(baselineText, current, spans, proposals, { pinned: baseline?.reason === "pinned" }),
      epoch: this.epochLabel(baseline),
      summary,
      authorable,
    });
  }

  /** F10 (PUC-6): off-panel proposal indicator on the active doc. Hidden when a panel is open. */
  private updateStatus(uri: string): void {
    const doc = vscode.workspace.textDocuments.find((d) => d.uri.toString() === uri);
    if (!doc) {
      this.hideStatus();
      return;
    }
    const n = this.proposals.listProposals(doc).length;
    if (n === 0 || this.panels.has(uri)) {
      this.hideStatus();
      return;
    }
    this.statusItem.text = `$(comment-discussion) ${n} Claude proposal${n === 1 ? "" : "s"}`;
    this.statusItem.tooltip = "Cowriting: open the review preview to accept/reject Claude's proposals";
    this.statusItem.show();
  }

  /**
   * Hide the off-panel indicator AND clear its text, so the `statusText()` seam
   * is honest: a hidden indicator reports `undefined` (not its stale last value).
   */
  private hideStatus(): void {
    this.statusItem.text = "";
    this.statusItem.hide();
  }

  private epochLabel(baseline: { reason: string; capturedAt: string } | undefined): string {
    if (!baseline) return "not coediting (no baseline yet)";
    const time = new Date(baseline.capturedAt).toLocaleTimeString();
    switch (baseline.reason) {
      case "head":
        return `HEAD ${time}`;
      case "pinned":
        return `reviewed ${time}`;
      default:
        return `entered ${time}`;
    }
  }

  private shellHtml(webview: vscode.Webview): string {
    const nonce = randomBytes(16).toString("base64");
    const scriptUri = webview.asWebviewUri(
      vscode.Uri.joinPath(this.extensionUri, "out", "media", "preview.js"),
    );
    const styleUri = webview.asWebviewUri(
      vscode.Uri.joinPath(this.extensionUri, "out", "media", "preview.css"),
    );
    // Sealed CSP (INV-21): no network. 'unsafe-inline' style is required only for
    // mermaid's dynamically injected <style> tags; scripts are nonce-gated and
    // strictly local (no remote/CDN script source).
    const csp =
      `default-src 'none'; ` +
      `img-src ${webview.cspSource} data:; ` +
      `font-src ${webview.cspSource}; ` +
      `style-src ${webview.cspSource} 'unsafe-inline'; ` +
      `script-src 'nonce-${nonce}';`;
    return `<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8" />
  <meta http-equiv="Content-Security-Policy" content="${csp}" />
  <link href="${styleUri}" rel="stylesheet" />
  <title>Track changes</title>
</head>
<body>
  <div id="cw-header">
    <label id="cw-toggle"><input type="checkbox" id="cw-annotations" checked /> Annotations</label>
    <button id="cw-pin" type="button" title="Pin the review baseline to now (clears the change-marks)">⌖ Pin baseline</button>
    <button id="cw-ask" type="button" title="Ask Claude to edit (the selection if any, else the whole document)">✦ Ask Claude to Edit Document</button>
    <button id="cw-acceptall" type="button" hidden title="Accept every pending Claude proposal on this document">✓✓ Accept all</button>
    <span id="cw-epoch">Review</span>
    <span id="cw-summary"></span>
    <span id="cw-legend"></span>
  </div>
  <div id="cw-body"></div>
  <script nonce="${nonce}" src="${scriptUri}"></script>
</body>
</html>`;
  }

  // ---- test seam (§6.4) ----
  isOpen(uriString: string): boolean {
    return this.panels.has(uriString);
  }
  /**
   * F11 test seam: deliver an inbound webview message to the real routing, as if
   * the sealed webview had posted it. Exercises message→seam wiring without a
   * live webview DOM (which is manual-smoke only). No-op if no doc/panel.
   */
  receiveMessage(uriString: string, m: ToolbarMsg): void {
    const doc = vscode.workspace.textDocuments.find((d) => d.uri.toString() === uriString);
    if (doc && this.panels.has(uriString)) this.handleWebviewMessage(doc, m);
  }
  /**
   * F11 (PUC-1/7): whether the previewed doc's edit controls (Pin + Ask-Claude)
   * are enabled — true only for an authorable doc. The annotations toggle is
   * always active (reading is always allowed). False if no panel/doc.
   */
  editControlsEnabled(uriString: string): boolean {
    const doc = vscode.workspace.textDocuments.find((d) => d.uri.toString() === uriString);
    return doc ? isAuthorable(doc.uri.scheme) : false;
  }
  getLastModel(uriString: string): BlockOp[] | undefined {
    return this.lastModel.get(uriString);
  }
  /** F10 test seam: the review HTML the panel would post for a doc (on-state). */
  renderHtmlFor(uriString: string): string {
    const doc = vscode.workspace.textDocuments.find((d) => d.uri.toString() === uriString);
    if (!doc) return "";
    const current = doc.getText();
    const baseline = this.diffView.getBaseline(uriString);
    return renderReview(
      baseline?.text ?? current,
      current,
      this.attribution.spansFor(doc),
      this.proposals.listProposals(doc),
      { pinned: baseline?.reason === "pinned" },
    );
  }
  /** F10: current annotations mode for a panel (default on). */
  getMode(uriString: string): "on" | "off" {
    return this.mode.get(uriString) ?? "on";
  }
  /** F10: set the annotations mode and re-render (the programmatic twin of the header toggle). */
  setMode(uriString: string, mode: "on" | "off"): void {
    this.mode.set(uriString, mode);
    const doc = vscode.workspace.textDocuments.find((d) => d.uri.toString() === uriString);
    if (doc) this.refresh(doc);
  }
  /** F10 test seam (SLICE-4 E2E): the off-panel status-bar indicator text, if shown. */
  statusText(): string | undefined {
    return this.statusItem.text || undefined;
  }

  dispose(): void {
    for (const t of this.debounces.values()) clearTimeout(t);
    for (const p of this.panels.values()) p.dispose();
    for (const d of this.disposables) d.dispose();
  }
}